Ask a Doubt
Request a call back

Join NOW to get access to exclusive study material for best results

JEE Class main Answered

In the above question if the charge distributed is changed as shown in figure, the force on q is 
question image
Asked by anshuman.anshuman090 | 06 Apr, 2019, 21:12: PM
answered-by-expert Expert Answer
Let us consider a small element dl in the ring that gives a repulsive force F to the charge q placed at the centre.
Force F can be resolved along horizontal direction as Fsinθ and in vertical direction as Fcosθ.
Horizontal component Fsinθ will be canceld out if we consider similar element of the ring in right side.
 
Hence the net force F+ due to positive charge distribution is given by

begin mathsize 12px style F subscript plus space equals space integral subscript negative straight pi divided by 2 end subscript superscript plus straight pi divided by 2 end superscript F cos theta space space equals space integral subscript negative straight pi divided by 2 end subscript superscript plus straight pi divided by 2 end superscript fraction numerator q space lambda subscript 2 d l over denominator 4 πε subscript straight o straight r squared end fraction cos theta space equals space fraction numerator q lambda subscript 2 over denominator 4 πε subscript straight o straight r squared end fraction integral subscript negative straight pi divided by 2 end subscript superscript plus straight pi divided by 2 end superscript cos theta space r d theta space equals space fraction numerator q lambda subscript 2 over denominator 4 πε subscript straight o straight r end fraction integral subscript negative straight pi divided by 2 end subscript superscript plus straight pi divided by 2 end superscript cos theta space d theta space equals space fraction numerator 2 q lambda subscript 2 over denominator 4 πε subscript straight o straight r end fraction end style ..........................(1)
In the above eqn.(1), λ2 is the charge density per unit length.
 
Similarly attractive force F- due to negative charge distribution is also proportional to charge density λ1
 
Both tthe forces are acting in same direction. Hence total force = begin mathsize 12px style fraction numerator 2 q over denominator 4 πε subscript straight o straight r end fraction open parentheses lambda subscript 1 space plus space lambda subscript 2 close parentheses space N e w t o n end style
Answered by Thiyagarajan K | 06 Apr, 2019, 22:57: PM

Application Videos

Concept Videos

Multiple Choice Questions Practice Test
Answered Unanswered My Questions My Answers
JEE main - Physics
a marble block of mass 2 kg lying on ice when a given velocity of 6 ms–1 is stopped by friction in 10 seconds then co efficient of friction is
Asked by sumalathamadarapu9 | 23 Oct, 2024, 22:06: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
show that the frequency of oscillations remain unchanged whether a mass attached to a spring is made to oscillate in the vertical or in the horizontal direction
Asked by py309649 | 13 Oct, 2024, 13:39: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
Square of the time period of revolution of a planet is proportional to the cube of the mean distance between sun and planet. If mean distance is increased by 2% then percentage change in its time period is
Asked by coolskrish | 13 Oct, 2024, 12:50: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
two particles of mass m and 4m are initially actress the sad moving towards each other due to mutual gravitational force at an instantly of m is vî then at this instant the velocity of mass 4m is
Asked by midnightmoon3355 | 09 Oct, 2024, 09:09: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
what is the second law of thermodynamics
Asked by rambabunaidu4455 | 03 Oct, 2024, 16:03: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
what is the relation between drift velocity and mobility
Asked by ratchanavalli07 | 17 Sep, 2024, 07:46: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
A ball of mass m approaches a moving wall of infinite mass with speed v along the normal to the wall. The speed of the ball is u towards the ball. The speed of the ball after elastic collision with the wall is
Asked by yayashvadutta45 | 15 Sep, 2024, 19:47: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
a current of 2a is flowing through a conductor of length 22m bent in arc radius 5cm
Asked by adithireddy999 | 03 Sep, 2024, 09:35: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
two vectors vector a and vector B lie in one plane vector c lie in the different plane then vector a + vector b + vector c is
Asked by vaishalinirmal739 | 29 Aug, 2024, 18:07: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
JEE main - Physics
What is impulse?
Asked by vradhysyam | 26 Aug, 2024, 17:17: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
My Class Videos Tests ₹ Plans Ask a Doubt